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Diagnostic beam absorber in Mu2e beam line

Description: Star density, hadron flux, and residual dose distributions are calculated around the {mu}2e diagnostic beam absorber. Corresponding surface and ground water activation, and air activation are presented as well.
Date: March 1, 2011
Creator: Rakhno, Igor
Partner: UNT Libraries Government Documents Department

Potential dose distributions at proposed surface radioactvity clearance levels resulting from occupational scenarios.

Description: The purpose of this report is to evaluate the potential dose distribution resulting from surface radioactivity, using occupational radiation exposure scenarios. The surface radioactivity clearance values considered in this analysis may ultimately replace those currently specified in the U.S. Department of Energy (DOE) requirements and guidance for radiological protection of workers, the public and the environment. The surface contamination values apply to radioactive contamination deposited on a surface (i.e., not incorporated into the interior of the material). For these calculations, the dose coefficients for intake of radionuclides were taken from ICRP Publication 68 (ICRP 1994), and external exposure dose coefficients were taken from the compact disc (CD) that accompanied Federal Guidance Report (FGR) 13 (Eckerman et al. 1999). The ICRP Publication 68 dose coefficients were based on ICRP Publication 60 (ICRP 1990) and were used specifically for worker dose calculations. The calculated dose in this analysis is the 'effective dose' (ED), rather than the 'effective dose equivalent' (EDE).
Date: August 2, 2011
Creator: Kamboj, S.; Yu, C. & Rabovsky, J.
Partner: UNT Libraries Government Documents Department

Treatment of patient-dependent beam modifiers in photon treatments by the Monte Carlo dose calculation code PEREGRINE

Description: The goal of the PEREGRINE Monte Carlo Dose Calculation Project is to deliver a Monte Carlo package that is both accurate and sufficiently fast for routine clinical use. One of the operational requirements for photon-treatment plans is a fast, accurate method of describing the photon phase-space distribution at the surface of the patient. The open-field case is computationally the most tractable; we know, a priori, for a given machine and energy, the locations and compositions of the relevant accelerator components (i.e., target, primary collimator, flattening filter, and monitor chamber). Therefore, we can precalculate and store the expected photon distributions. For any open-field treatment plan, we then evaluate these existing photon phase-space distributions at the patient`s surface, and pass the obtained photons to the dose calculation routines within PEREGRINE. We neglect any effect of the intervening air column, including attenuation of the photons and production of contaminant electrons. In principle, for treatment plans requiring jaws, blocks, and wedges, we could precalculate and store photon phase-space distributions for various combinations of field sizes and wedges. This has the disadvantage that we would have to anticipate those combinations and that subsequently PEREGRINE would not be able to treat other plans. Therefore, PEREGRINE tracks photons through the patient-dependent beam modifiers. The geometric and physics methods used to do this are described here. 4 refs., 8 figs.
Date: March 1, 1997
Creator: Schach von Wittenau, A.E.; Cox, L.J.; Bergstrom, P.M. Jr.; Hornstein, S.M.; Mohan, R.; Libby, B. et al.
Partner: UNT Libraries Government Documents Department

Radiation levels in the SSC interaction regions

Description: The radiation environment in a typical SSC detector has been evaluated using the best available particle production models coupled with Monte Carlo simulations of hadronic and electromagnetic cascades. The problems studied include direct charged particle dose, dose inside a calorimeter from the cascades produced by incident photons and hadrons, the flux of neutrons and photons backscattered from the calorimeter into a central cavity, and neutron flux in the calorimeter. The luminosity lifetime at the SSC is dominated by collision losses in the interaction regions, where the luminosity is equivalent to losing an entire full-energy proton beam into the apparatus every six days. The result of an average p-p collision can be described quite simply. The mean charged multiplicity is about 110, and the particles are distributed nearly uniformly in pseudorapidity ({eta}) over all the angles of interest. The transverse momentum distribution is independent of angle, and for our purposes may be written as p{perpendicular}exp(-p{perpendicular}/{beta}). The mean value of p{perpendicular} may be as high as 0.6 GeV/c. Most of the radiation is produced by the very abundant low-p{perpendicular} particles. The dose or neutron fluence produced by individual particles in this energy region are simulated over a wide variety of conditions, and several measurements serve to confirm the simulation results. In general, the response (a dose, fluence, the number of backscattered neutrons, etc.) for an incident particle of momentum p can be parameterized in the form Np{sup {alpha}}, where 0.5 < {alpha}< 1.0. The authors believe most of their results to be accurate to within a factor of two or three, sufficiently precise to serve as the basis for detailed designs.
Date: June 10, 1988
Creator: Groom, D.E.
Partner: UNT Libraries Government Documents Department

Uniform dose distribution with moving negative pion beams

Description: Dense ionization in the stopping region as negative pions come to rest in matter makes them attractive for treatment of cancer. Pions of the same energy have essentially the same range in matter which means that a monoenergetic beam will produce a Bragg peak region of maximum ionization as they come to rest. In cancer therapy, the entire treatment volume should be exposed, if possible, to the Bragg peak. A distribution of energy and adjustment of lateral dimensions could theoretically adjust the Bragg peak to fit into most any treatment volume but this inight be difficult in practice to accomplish. As an alternative, the beam can be tuned to produce a peak with known properties, and this peak can be moved in a controlled manner so as to scan the treatment volume. For a vertical beam, this method usually will require vertical oscillations of the beam as well as horizontal motion to cover the entire volume. Both of these motions can result in undesirable dose distributions. It is shown how to avoid or minimize the unwanted effects and it is also shown how velocity distributions can be determined for uniform effective dose throughout a treatment volume. (auth)
Date: July 1, 1973
Creator: Rodgers, E.
Partner: UNT Libraries Government Documents Department

Investigations into the Optimization of Multi-Source Strength Brachytherapy Treatment Procedures

Description: The goal of this project is to investigate the use of multi-strength and multi-specie radioactive sources in permanent prostate implant brachytherapy. In order to fulfill the requirement for an optimal dose distribution, the prescribed dose should be delivered to the target in a nearly uniform dose distribution while simultaneously sparing sensitive structures. The treatment plan should use a small number of needles and sources while satisfying the treatment requirements. The hypothesis for the use of multi-strength and/or multi-specie sources is that a better treatment plan using fewer sources and needles could be obtained than by treatment plans using single-strength sources could reduce the overall number of sources used for treatment. We employ a recently developed greedy algorithm based on the adjoint concept as the optimization search engine. The algorithm utilizes and ''adjoint ratio'', which provides a means of ranking source positions, as the pseudo-objective function. It ha s been shown that the greedy algorithm can solve the optimization problem efficiently and arrives at a clinically acceptable solution in less than 10 seconds. Our study was inclusive, that is there was no combination of sources that clearly stood out from the others and could therefore be considered the preferred set of sources for treatment planning. Source strengths of 0.2 mCi (low), 0.4 mCi (medium), and 0.6 mCi (high) of {sup 125}I in four different combinations were used for the multi-strength source study. The combination of high- and medium-strength sources achieved a more uniform target dose distribution due to few source implants whereas the combination of low-and medium-strength sources achieved better sparing of sensitive tissues including that of the single-strength 0.4 mCi base case. {sup 125}I at 0.4 mCi and {sup 192}Ir at 0.12 mCi and 0.25 mCi source strengths were used for the multi-specie source study. This study also proved inconclusive ...
Date: September 30, 2002
Creator: Henderson, D. L.; Yoo, S. & Thomadsen, B.R.
Partner: UNT Libraries Government Documents Department

Fast Monte Carlo for radiation therapy: the PEREGRINE Project

Description: The purpose of the PEREGRINE program is to bring high-speed, high- accuracy, high-resolution Monte Carlo dose calculations to the desktop in the radiation therapy clinic. PEREGRINE is a three- dimensional Monte Carlo dose calculation system designed specifically for radiation therapy planning. It provides dose distributions from external beams of photons, electrons, neutrons, and protons as well as from brachytherapy sources. Each external radiation source particle passes through collimator jaws and beam modifiers such as blocks, compensators, and wedges that are used to customize the treatment to maximize the dose to the tumor. Absorbed dose is tallied in the patient or phantom as Monte Carlo simulation particles are followed through a Cartesian transport mesh that has been manually specified or determined from a CT scan of the patient. This paper describes PEREGRINE capabilities, results of benchmark comparisons, calculation times and performance, and the significance of Monte Carlo calculations for photon teletherapy. PEREGRINE results show excellent agreement with a comprehensive set of measurements for a wide variety of clinical photon beam geometries, on both homogeneous and heterogeneous test samples or phantoms. PEREGRINE is capable of calculating >350 million histories per hour for a standard clinical treatment plan. This results in a dose distribution with voxel standard deviations of <2% of the maximum dose on 4 million voxels with 1 mm resolution in the CT-slice plane in under 20 minutes. Calculation times include tracking particles through all patient specific beam delivery components as well as the patient. Most importantly, comparison of Monte Carlo dose calculations with currently-used algorithms reveal significantly different dose distributions for a wide variety of treatment sites, due to the complex 3-D effects of missing tissue, tissue heterogeneities, and accurate modeling of the radiation source.
Date: November 11, 1997
Creator: Hartmann Siantar, C.L.; Bergstrom, P.M.; Chandler, W.P.; Cox, L.J.; Daly, T.P.; Garrett, D. et al.
Partner: UNT Libraries Government Documents Department

Development of dosimetric approaches to treatment planning for radioimmunotherapy. Annual report 1989--1990

Description: The objective of quantitative imaging is to provide pharmacokinetic information for patients that is analogous to that provided by biodistribution studies in mice. Radionuclide images depict the distribution of labeled antibodies in-vivo; thus the amount of radionuclide in a specific organ or site can be estimated by relating the counts detected in a defined region of interest to the total radionuclide content. This pharmacokinetic information can be used to obtain definitive and relevant answers to basic questions of importance for optimizing radioimmunoimaging and radioimmunotherapy and, in addition, can provide a data base from which to calculate the distribution of radiation absorbed doses. The research employs quantitative imaging in evaluating therapies. Quantitative imaging is performed by a certified nuclear medicine technician using the Siemens gamma camera interfaced with the microVAX II. The technician processes the imaging data and obtains pharmacokinetic information from it using programs developed by the authors and others. A large amount of data has been acquired and analyzed on the pharmacokinetics, dosimetry and toxicity of radiolabeled monoclonal therapy. Important dosimetry data on the whole body, marrow and tumor doses are available and all studies are archived so that they can be retrospectively analyzed. Although the radiation absorbed doses delivered to tumor sites were modest, significant biological responses were found.
Date: December 31, 1990
Creator: DeNardo, S.J.
Partner: UNT Libraries Government Documents Department

Dose and volume specification for reporting interstitial therapy

Description: The ICRU has previously published reports dealing with Dose Specification for Reporting External Beam Therapy with Photons and Electrons (ICRU Report 29, ICRU, 1978), Dose Specification for Reporting External Beam Therapy (ICRU Report 50, ICRU, 1993) and Dose and Volume Specification for Reporting Intracavitary Therapy in Gynecology (ICRU Report 38, ICRU, 1985). The present report addresses the problem of absorbed dose specification for report interstitial therapy. Although specific to interstitial therapy, many of the concepts developed in this report are also applicable to certain other kinds of brachytherapy applications. In particular, special cases of intraluminal brachytherapy and plesio-brachytherapy via surface molds employing x or gamma emitters are addressed in this report.
Date: December 30, 1997
Partner: UNT Libraries Government Documents Department

Conditions Around the Proton Beam Window of the Spallation Neutron Source

Description: A proton beam window separates regions with different vacuum conditions in the last part of the path of the proton beam. Very near to the window an instrumentation box for beam diagnostics is going to be located. All components comprising the proton beam window assembly are going to be located in a box, which has to be serviced regularly through a channel perpendicular to the direction of the beam (2mA 1 GeV protons). Due to the strong effects of the proton window, the engineering design of this part of the target facility requires detailed calculations of the heating and dose distributions for beam on and off conditions as a function of the materials for the window and the shielding of the instrumentation box. A summary of the results, relevant to decisions to be taken regarding the design and operation of the facility, are presented.
Date: August 31, 2001
Creator: Difilippo, FC
Partner: UNT Libraries Government Documents Department

Distribution of absorbed doses in the materials irradiated by ''RHODOTRON'' electron accelerator: Experiment and Monte Carlo simulations

Description: This paper describes the experimental setup and presents studies of absorbed doses in different metals and dielectrics along with corresponding Monte Carlo energy deposition simulations. Experiments were conducted using a 5 MeV electron accelerator. We used several Monte Carlo code systems, namely MARS, MCNP, and GEANT to simulate the absorbed doses under the same conditions as in experiment. We compare calculated and measured high and low absorbed doses (from few kGy to hundreds kGy) and discuss the applicability of these computer codes for applied accelerator dosimetry.
Date: July 2, 2001
Creator: al., Oleg E. Krivosheev et
Partner: UNT Libraries Government Documents Department

Occupational radiation exposure at commercial nuclear power reactors and other facilities 1996: Twenty-ninth annual report. Volume 18

Description: This report summarizes the occupational exposure data that are maintained in the US Nuclear Regulatory Commission`s (NRC) Radiation Exposure Information and Reporting System (REIRS). The bulk of the information contained in the report was compiled from the 1996 annual reports submitted by six of the seven categories of NRC licensees subject to the reporting requirements of 10 CFR 20.2206. Since there are no geologic repositories for high level waste currently licensed, only six categories will be considered in this report. Annual reports for 1996 were received from a total of 300 NRC licensees, of which 109 were operators of nuclear power reactors in commercial operation. Compilations of the reports submitted by the 300 licensees indicated that 138,310 individuals were monitored, 75,139 of whom received a measurable dose. The collective dose incurred by these individuals was 21,755 person-cSv (person-rem){sup 2} which represents a 13% decrease from the 1995 value. The number of workers receiving a measurable dose also decreased, resulting in the average measurable dose of 0.29 cSv (rem) for 1996. The average measurable dose is defined to be the total collective dose (TEDE) divided by the number of workers receiving a measurable dose. These figures have been adjusted to account for transient reactor workers. Analyses of transient worker data indicate that 22,348 individuals completed work assignments at two or more licensees during the monitoring year. The dose distributions are adjusted each year to account for the duplicate reporting of transient workers by multiple licensees. In 1996, the average measurable dose calculated from reported was 0.24 cSv (rem). The corrected dose distribution resulted in an average measurable dose of 0.29 cSv (rem).
Date: February 1, 1998
Creator: Thomas, M.L. & Hagemeyer, D.
Partner: UNT Libraries Government Documents Department

Clinical implementation of the Peregrine Monte Carlo dose calculations system for photon beam therapy

Description: PEREGRINE is a 3D Monte Carlo dose calculation system designed to serve as a dose calculation engine for clinical radiation therapy treatment planning systems. Taking advantage of recent advances in low-cost computer hardware, modern multiprocessor architectures and optimized Monte Carlo transport algorithms, PEREGRINE performs mm-resolution Monte Carlo calculations in times that are reasonable for clinical use. PEREGRINE has been developed to simulate radiation therapy for several source types, including photons, electrons, neutrons and protons, for both teletherapy and brachytherapy. However the work described in this paper is limited to linear accelerator-based megavoltage photon therapy. Here we assess the accuracy, reliability, and added value of 3D Monte Carlo transport for photon therapy treatment planning. Comparisons with clinical measurements in homogeneous and heterogeneous phantoms demonstrate PEREGRINE's accuracy. Studies with variable tissue composition demonstrate the importance of material assignment on the overall dose distribution. Detailed analysis of Monte Carlo results provides new information for radiation research by expanding the set of observables.
Date: July 1, 1999
Creator: Albright, N; Bergstrom, P M; Daly, T P; Descalle, M; Garrett, D; House, R K et al.
Partner: UNT Libraries Government Documents Department

Personnel exposure experience related to use of $sup 252$Cf sources

Description: Studies are presented of personnel exposures to $sup 252$Cf neutrons and gamma radiation during dosimetry experiments in mouse phantoms, fission foil detectors, and small tissue equivalent ionization chambers. Sensitivity of film badge emulsions to observed levels of $sup 252$Cf neutrons is discussed. Long- term personnel exposure histories are presented. Comparisons are made between neutron dose calculated from observed neutron-gamma ratios and the dose observed in neutron emulsions. Shielding used during experiments is described. (auth)
Date: January 1, 1976
Creator: Mason, E.W.; Moser, F. & Lanzl, L.H.
Partner: UNT Libraries Government Documents Department

Improvements in Monte Carlo Simulation of Large Electron Fields

Description: Two Monte Carlo systems, EGSnrc and Geant4, were used to calculate dose distributions in large electron fields used in radiotherapy. Source and geometry parameters were adjusted to match calculated results with measurement. Both codes were capable of accurately reproducing the measured dose distributions of the 6 electron beams available on the accelerator. Depth penetration was matched to 0.1 cm. Depth dose curves generally agreed to 2% in the build-up region, although there is an additional 2-3% experimental uncertainty in this region. Dose profiles matched to 2% at the depth of maximum dose in the central region of the beam, out to the point of the profile where the dose begins to fall rapidly. A 3%/3mm match was obtained outside the central region except for the 6 MeV beam, where dose differences reached 5%. The discrepancy observed in the bremsstrahlung tail in published results that used EGS4 is no longer evident. The different systems required different source energies, incident beam angles, thicknesses of the exit window and primary foils, and distance between the primary and secondary foil. These results underscore the requirement for an experimental benchmark of electron scatter for beam energies and foils relevant to radiotherapy.
Date: November 28, 2007
Creator: Faddegon, Bruce A.; /UC, San Francisco; Perl, Joseph; Asai, Makoto & /SLAC
Partner: UNT Libraries Government Documents Department

Fundamental limitations of LIGA x-ray lithography : sidewall offset, slope and minimum feature size.

Description: Analytical and numerical methods are used to examine photoelectron doses and their effect on the dimensions of features produced by deep x-ray lithography. New analytical models describing electron doses are presented and used to compute dose distributions for several feature geometries. The history of development and final feature dimensions are also computed, taking into account the dose field, dissolution kinetics based on measured development rates, and the transport of PMMA fragments away from the dissolution front. We find that sidewall offsets, sidewall slope and producible feature sizes all exhibit at least practical minima and that these minima represent fundamental limitations of the LIGA process. The minimum values under optimum conditions are insensitive to the synchrotron spectrum, but depend strongly on resist thickness. This dependence on thickness is well approximated by simple analytical expressions describing the minimum offset, minimum sidewall slope, minimum producible size of positive and negative features, maximum aspect ratio and minimum radius of inside and outside corners.
Date: January 1, 2004
Creator: Griffiths, Stewart K.
Partner: UNT Libraries Government Documents Department